Mandrel threading apparatus



N 1966 J. E. GREENLAY ETAL 3,285,856

MANDREL THREADING APPARATUS Filed Aug. 2, 1965 PATEN f1 AGENT United States Patent 3,286,856 MANDREL THREADING APPARATUS John E. Greenlay, Rosemount, Montreal, Quebec, and

Bernard A. Berger, Montreal, Quebec, Canada, assignors to Northern Electric Company Limited, Montreal,

Quebec, Canada Filed Aug. 2, 1965, Ser. No. 476,356 13 Claims. (Cl. 2148) This invention relates to an apparatus for threading articles having a central bore therethrough onto a wire mandrel, and more particularly, to an apparatus for threading hollow rivets onto a removable wire storage mandrel of a riveting machine.

It is common practice when riveting together parts, and particularly, mass produced sheet metal parts such as those encountered in the manufacture of aircraft, missiles, automobile and electronic chassis, to use a riveting gun having a demountable wire mandrel on which hollow rivets are stored and which mandrel also serves as the riveting anvil. It has been past practice in such riveting processes to remove the empty wire mandrel from the gun and completely separate from the gun to feed the rod through a stack of the rivets rolled in a tube of aluminum foil or similar wrapping material. After the mandrel is inserted through the aligned central bores of the rivets, the tubular Wrapping is removed and discarded, and the mandrel with the rivets threaded thereon is replaced in the gun. The gun is then operated until the mandrel is stripped of rivets, and the mandrel is again removed and reloaded as just described. It can 'be appreciated that with this previously used process, the cost of the riveting operation includes the packaging of the rivets into the tubular wrapping, and the extra cost due to packaging of the rivets can be substantial when a large number of rivets are used in an operation.

It is an object of the present invention to provide an apparatus which can be operated at the riveting site and is capable of automatically loading one of the mandrels from a bulk supply of rivets while a previously loaded mandrel is being used for riveting in the gun.

According to the present invention, which is designed to thread articles having a central bore such as rivets, onto a wire mandrel, there is provided an article retaining means having an article receiving opening therethrough, and a mandrel supporting means at one side of the retaining means for holding the mandrel with one free end projecting into the opening. The retaining means has a resilient means about its opening for engaging one of the articles and frictionally retaining it in the opening with the free end of the mandrel projecting into the bore of the article to thereby centralize the free end in the opening. There is also provided a holding means adjacent the opposite side of the retaining means as the mandrel supporting means and adapted to hold another of the articles with the bore aligned with the central axis of the opening in said retaining means, means for feeding articles one at a time into the holding means, and a press means for pushing the article held in the holding means into the opening in the retaining means to thereby replace the article in the opening whereby it will be released from the retaining means to slide freely along the mandrel.

Preferably the retaining means comprises a plate member having the article receiving opening extending therethrough, the plate defining a plurality of radially extending bores communicating with the opening in the plate member, and article engaging pins, one pin being in each bore and being spring biased towards the opening in the plate member.

In the accompanying drawings which show, by way of examples, certain embodiments of the present invention:

FIGURE 1 is a side perspective view of one embodi- A 3,286,856 Patented Nov. 22, 1966 ice ment of the apparatus according to the present invention;

FIGURE 2 is an enlarged perspective view of the working parts at the upper end of the mandrel in the apparatus shown in FIGURE 1;

FIGURE 3 is a top view of a rivet retaining means according to the present invention;

FIGURE 4 is a sectional view through the rivet engaging pins in the rivet retaining means; and

FIGURE 5 is a partially exploded perspective view of another embodiment of a rivet holding means which may be used in the apparatus shown in FIGURE 1.

Referring now mainly to FIGURE 1, the reference character 10 denotes generally the rivet threading apparatus of the present invention. The apparatus 10 has a frame 11 on which is mounted a feed means 12 including a conventional vibratory hopper 13 of the type having a spiral peripheral feed track 14 for guiding the rivets one after another along to an exit 15. A transfer means 16 is provided at the exit 15 for delivering one rivet at atime sideways into a holding means 17. Under the holding means 17 is mounted a rivet retaining means 18 and above holding means 17 a press means 19 is provided for pushing a rivet from the holding means 17 down into the retaining means 18. Below retaining means 18 a mandrel supporting means 20 is carried by the frame 11, the means 20 being arranged to carry a relatively long wire mandrel 21 on which rivets 22 are threaded by the apparatus 10. As may be most readily observed in FIGURES 2 and 4, the rivets 22 are of the type having a shank portion and an enlarged head portion with a central longitudinal bore through the length thereof, although it is obvious that the machine could be used for threading straight cylindrical or other shaped objects having a central bore.

As shown in FIGURES 1 and 2, the frame 11 includes a long vertical section 25 of channel cross-section, and in the very top of vertical section 25, the retaining means 18 is fixed. The retaining means 18 is formed by two substantially square plate members 26 and 26a, one mounted ontop of the other. The plates 26 and 26a, which are substantially equal in thickness to the length of the rivet, have aligned rivet receiving central openings 27 and 27a (see FIGURES 3 and 4) extending vertically therethrough. Plate members 26 and 26a are provided with four radially extending bores 28 which communicate with the central opening 27, and in the case of plate 26 these bores extend diagonally as shown in FIGURE 3. In each bore a pin 30 is reciprocably mounted with an inner rivet engaging end surface 31 in the opening 27. As shown in FIGURE 4, the pins 30 are nearly as deep as the plate 26 and the surface 31 is of conical contour, i.e., the surface 31 is concave in cross-section and tapers downwardly, so that the pins engage both the head and shank portions of the rivet to hold them in a vertically disposed position. Screws 32 are threaded onto the outer ends of the bores 28 and coil springs 33 are compressed between each screw 32 and pin 30 so that the pins are biased inwardly towards the opening 27. The plate member 26a is nearly identical to plate member 26 except in plate member 26a the bores are at right angles to the side edges instead of diagonal so that the pins 30a are 45 f out of phase with the pins 30.

In the embodiment of the invention shown in FIG- URES 1, 2 and 4 the rivet holding means includes a pair of jaw members 34, 34 each of which is pivotally connected to the frame 11 by a screw member 35 (see FIG- URE 2). The jaw members 34, 34 are provided at one end with opposed rivet engaging surfaces 36, 36, and a compressed coil spring 37 between the opposite ends of the jaw member biases the rivet engaging surfaces to a rivet clamping position directly over the central opening 27a. in plate member 26a. In between the surfaces 36, 36 and the points where the jaw members are pivotally connected to thE frame, the jaw members are provided with spaced plunger engaging surfaces 38, 38.

The press means 19 is located above the holding means 18 and includes a double acting cylinder and piston type pneumatic motor 40 mounted above a stationary horizontal plate 41 which forms part of the frame 11. Air under pressure is fed alternately to opposite sides of the piston in motor 40 through 'hoses 42 and 43, the timing of the flow of air being carried out by well-known solenoids and .valves which may be controlled by switches operated by the stroke of the motor itself, or otherwellknown timing means may be utilized. A piston rod 44 connected to the piston in the motor 40 extends through. an opening in plate 41 and is connected to a crosshead 45, which of course, reciprocates upwardly and downwardly with the stroke of the motor 40. On the bottom of crosshead 45 are mounted side by side a ram 46 and a tapered plunger 47. The ram 46 is aligned so that its lower end surface 50 (see FIGURE 4) engages a rivet held'between surfaces 36, 36 of the jaw members 34, 34 on the downward stroke of the crosshead 45. The ram 46 has a longitudinal bore 51 extending to its lower end surface 50, and a spring biased rivet guiding pin 52 is mounted in the bore 51 and retractably projects downwardly from lower end surface 50, the pin 52 being of a diameter to closely fit in the central bore of the rivets. The tapered plunger 47 is positioned on the crosshead 45 to move between surf-aces 38, 38 of the jaw members 34, 34 on the downward stroke to thereby separate the rivet engaging surfaces 36, 36 against the biasingeffect of spring 37.

As previously described, the vibratory hopper 13 feeds the rivets one after another to the exit 15. The rivets reach the exit with the head portion thereof up and are permitted to enter a guideway 55 of the transfer means 16 one at a time. The guideway which is shown covered in FIGURE 2 has a longitudinally extending channel 56 which in cross-section is the same shape as the rivets as shown in phantom in FIGURE 5, i.e., the channel 56 has in cross-section a narrow and deep shank receiving portion and a wider and shallow head receiving portion, so that the rivet can be pushed sideways through the channel 56. The channel. 56 is aligned with minates at the space between the rivet engaging surface 36, 36 of the jaw members 34, 34, and at one side communicates with the exit of the vibratory hopper 13. The transfer means 16 also includes a horizontally extending pneumatically operated plunger 57 which reciprocates in channel 56 for pushing a rivet sideways from the exist 15 into the jaw members 34, 34. The plunger 57 is actuated by a pneumatic motor 60 mounted on a bracket 61 of frame 11. The motor is of the cylinder and piston type, the plunger 57 being connected to the rod of the piston in the cyinder. The motor 60 is also of the type in which the piston is spring-biased to a retracted position and air entering through hose 62 forces the piston against the spring force to project the piston rod and thereby pushes plunger 57 to deposit a rivet in the jaw members 34, 34. When the hose 62 is vented to atmosphere the plunger is returned by the spring force past the exit 15 of the vibratory hopper 13 so that another rivet can enter guideway 55. The timing of the How of air in 'hose 62 is controlled by the same means which controls the operation of motor 40 so that the motor 60 completes its cycle as ram 46 engages the rivet held by jaw members. 34, 34 to push the rivet just deposited by plunger 57 down into the retaining means 18.

The mandrel supporting means consists of a tubular member 65 which is held vertically in the lower portion of vertical section of the frame. A guide block 66 fixed within vertical section 25 holds the upper end of the tubular member 65 in place and fixed to bottom end plate 67 of the tubular member is a downwardly projecting pin 70 which passes through an opening in a guide block 68 of the vertical section 25. The tubular member .ings of the plate members 26 and 26a.

end plate 67. With the lower end of the mandrel in tubular member 67, the mandrel is vertically supported with its upper free end projecting through the opening 27 in lower plate. member 26 as shown in FIGURE 4.

Under guide block 68 is mounted an electrical switch 72 having a switch arm positioned to be engaged by pin 70 on downward displacement of the tubular member 65 to open the switch. The switch 72 is in series with a main control switch 73 for the vibratory hopper 13 and the solenoids controlling the air to motors 40 and 60 so that as tubular member 65 is displaced downwardly against the biasing effect of spring 71 the machine is shut down by switch 72.

In operation the apparatus is set up near the riveting station and connected to an apropriate source of electricity and compressed air. The vibratory hopper 13 is filled from a bulk supply of rivets and an empty mandrel is inserted into tubular member 67 with its upper free end projecting into the central opening 27" in plate member 26. One rivet is pushed downwardly into the opening 27 by hand and the upper end of the mandrel is directed into the bore of the rivet so that the mandrel is centralized in the opening 27. The .rivet is frictionally retained due to the engagement of'the pins 30 therewith as shown in FIGURE 4. Another rivet may be inserted into the opening 27a in a similar manner to be retained by pins 3011.. The machine is then started by switching on the main control switch 73. This starts the vibrating of vibratory hopper 13 and the rivets are fed properly oriented to exit 15. control means of the apparatus air is admitted through hose 62 to motor 60 which forces plunger 57 to engage one rivet, which has been fed from exit 15 into guideway 55, and push itsideways between surfaces 36,36

of jaw members 34, 34. As the rivet is pushed into the jaw member, they are forced open slightly against the biasing effect of spring 37 to receive the rivet;

Motor 60 is then vented to air to permit the plunger, 57 to return past the exitjlS under the action of the spring in motor 60. The next rivet is then forced into guideway 55 by the vibratory hopper 13. As. plunger 57 returns fromits work stroke air is admitted to; motor,

40 through hose 43 so that crosshead 45 is forced downwardly. When the crosshead moves downwardly the pin 52 enters the bore of the rivet held between surfaces 36, 36 and as the lower end surface 50 of ram 46 engages the top of the head portion of the rivet,

the tapered plunger 47 is forced between the plunger.

engaging surfaces 38,38 of the jaw members 34, 34. The plunger 45 thereby separates the jaw members 34,

34 to release the rivet held between surfaces 36,36

30a in plate member 26a is pushed down into the next of pins 30 in plate member 26 which pushes the rivet held by the bottom plate member out, and this released.

rivet is then free to slide down the mandrel until it engages tubular member 65. The cycle just described. is

repeated time after time and all of the time the upper free end of the mandrel is kept centralized in the opening due to the fact rivets are always maintained in the open- Any tendency Thus the lower end of the mandrel can be Under the of the rivets to tilt or become crooked as they enter the plate members is eliminated by the existence of guiding pin 52 in the bore of the rivet. As indicated above, the guiding pin 52 is retractable so that if it engages the upper end of the mandrel, it is simply pushed back into ram 46.

As the rivets are continuously threaded one at a time onto the mandrel as described above, the mandrel eventually accumulates a full stack of stored rivets. As this happens the force applied by ram 46 to the last rivet fed into the holding means 17 is transferred through the full stack of rivets to the top of tubular member 65, and the tubular member 65 is thus displaced slightly downwardly against the biasing effect of spring 71. The pin 70 thus engages switch 72 to automatically shut the machine off. The operator of the riveting machine then inserts the filled mandrel into the riveting machine, inserts an empty mandrel into the apparatus as previously described and restarts the apparatus. The new mandrel is then filled in exactly the same manner as described and is ready for insertion into the riveting machine before the rivets on the previously threaded mandrel are all used.

In place of the jaw members 34, 34 another type of holding means in the form of plate member 260 (FIG- URE 5) can be utilized. As can be readily observed, this alternative holding means is very similar to the plate members of the retaining means 18, and in fact exactly the same parts can be utilized, it being only necessary to cut one side of the plate member 26 away to provide an entrance 75 to permit one rivet at a time to be pushed horizontally from guideway 55 into opening 270 of plate member 260. The plate member 260 thus has only three bores 28c spaced at 90 and carrying pins 300. As can be seen in FIGURE 5, the bores 280 are provided with a narrower slot-like portion adjacent the opening 27c and pins 30 are like-shaped so as to provide engaging shoulders 76 which limit the inward travel of the pins. As in the case of plate member 26, the pins 300 are biased towards opening 270 by springs 37c compressed between the pins and screws 320.

In the operation of apparatus 10 with the holding means shown in FIGURE 5, it is not necessary to provide a tapered plunger 47 since ram 46 simply pushes the rivet held in opening 27c by pins 30c downwardly into the opening of the next plate member, and as the head portion of the rivet is pushed downwardly between the tapered end surfaces of the pins 30c, the pins 300 are forced back in bores 280 against the biasing effect of springs 37 in the same manner as pins 30 and 30a act when the rivets are pushed through the other two plates. After the rivet is pushed out of opening 27c, pins 300 move inwardly but their travel is limited by shoulders 76 so that the inner ends of the pins 300 are spaced sufficiently to permit the next rivet to be pushed into opening 270 and be gripped by the pins 300.

Certain further modifications could be made, of course, to the described apparatus without departing from the spirit of the invention, the scope of which is defined in the following claims. For example, regardless of the type of holding means 17 utilized, it is not absolutely essential to use two plate members 26 and 26a, i.e., it would be possible to use only plate member 26 as the retaining means. With only one plate member, such as plate member'26, in use, the upper end of the mandrel would still extend upwardly into the central opening but not entirely through it as shown in FIGURE 4, and the rivet would be pushed directly from the holding means directly into the immediately adjacent plate member. It has been found preferable, however, to utilize two plate members as shown in the drawings.

We claim:

1. An apparatus for threading articles each having a central bore therethrough onto a wire mandrel, said apparatus comprising an article retaining means having an article receiving opening therethrough, a mandrel supporting means at one side of said retaining means for holding the mandrel with one free end projecting into said opening, said retaining means having resilient means about said opening for engaging one of the articles and frictionally retaining said one article in said opening with the free end of the mandrel projecting into the bore of said one article to thereby centralize said free end in said opening, a holding means adjacent the opposite side of the retaining means as the mandrel supporting means and adapted to hold another of the articles with the bore thereof aligned with the central axis of the opening in said retaining means, means for feeding articles one at a time into said holding means, and a press means for pushing the article held in the holding means to thereby replace said one article in said opening whereby said one article will be released from said retaining means to slide freely along said mandrel.

2. An apparatus as defined in claim 1, wherein said retaining means comprises a plate member having the article receiving opening extending therethrough, said plate defining a plurality of radially extending bores communicating with said opening in said plate member, and article engaging pins, one pin being in each bore and being spring biased towards said opening in said plate member.

3. An apparatus as defined in claim 1, wherein said holding means comprises a plate member having an article receiving opening therethrough, said plate member defining a plurality of radially extending bores communicating with said opening in said plate member, article engaging pins, one pin being in each bore and being spring biased towards said opening in said plate member, and means defining a passageway for permitting sideways movement of one article at a time into said opening in the plate member.

4. An apparatus as defined in claim 1, wherein said holding means comprises a pair of jaw members having opposed article engaging surfaces, spring means engaging said jaws and biasing said surfaces towards each other to an article clamping position, and a plunger connected to said press means for engaging said jaws and separating said surfaces as said press mean pushes the article held by said holding means to the retaining means.

5. An apparatus for threading a plurality of small cylindrical articles onto a relatively long wire mandrel, said apparatus comprising a plate member having an article receiving opening extending vertically therethrough, a mandrel supporting means below said plate member and arranged to hold the lower end of the mandrel with the upper end of the mandrel projecting upwardly .and freely into said opening in said plate member, resilient article engaging means carried by said plate member and extending into said opening for frictionally retaining -'one of the articles in a position encircling the upper free end of the mandrel to thereby centralize the mandrel in said opening, a holding means immediately above said plate member for holding another of the articles axially aligned with the opening in the plate member, a feed means for moving said articles one after the other along a path to a point adjacent said holding means, a transfer means for delivering one article at a time sideways from said path and into said holding means, and a press means for pushing the article held in the holding means downwardly to replace the article retained in said plate member and thereby free the article retained in the plate member to slide down the mandrel and be stored there-on above said mandrel supporting means.

6. An apparatus as defined in claim 5, wherein said article engaging means carried by said plate member comprises a plurality of circumferentially spaced pins each recipnocably mounted in a bore in said plate member extending radially from said opening, said pins having 7 inner article engaging end surfaces in said opening and being biased inwardly by springs in said bores.

7. An apparatus as defined in claim 5, wherein said holding means comprises a second plate member having a vertical article receiving opening with a horizontal passageway for the sideways delivery of the article into the holding means, and a plurality of pins circumferentially spaced about the opening in the second plate member, each pin being reciprocably mounted in a bore extending radially from the opening in the second plate member, said pins being spring-biased inwardly for frictionally holding therebetween the article delivered through said passageway.

8. An apparatus as defined in claim 5, wherein said holding means comprises a pair of jaws spring-loaded towards an article gripping position, and wherein a tapered plunger is connected to said press means for separating said jaws to an article releasing position as said press means pushes the article downwardly into said opening in said plate member.

9. An apparatus as defined in claim 5, wherein said mandrel supporting means includes a vertically disposed tubular member having a mandrel carrying closed lower end and an opening in the upper end thereof for slidable reception of the lower end of the mandrel into the tubular member.

10.'An apparatus as defined in claim 9, and further comprising resilient means supporting said tubular member and permitting downward movement thereof under a load derived from the downward push of said press means on a full stack of articles on said mandrel, and a switch means under said tubular member arranged to be activated and thereby open an operating circuit of said feed means, transfer means and press means upon downward movement of said tubular member.

11. An apparatus for threading rivets of the type having a shank portion and a head portion with a central longitudinal bore through the length thereof onto a removable wire storage mandrel of a riveting machine, said apparatus comprising three horizontal plate members stacked one on top of the other and each of a thickness substantially equal to the rivet length, said plate members having aligned vertical openings extending therethrough, each of the plate members having a plurality of circumferentially spaced pins about each opening of the respective plate member, said pins being recipnocably mountedin bores in each plate member extending radially from the opening of the respective plate member, said pins in each plate member being spring-biased towards the opening of the respective plate member and having rivet engaging inner end surfaces of the conical contour in the opening for engaging both head and shank portions of the rivet to thereby frictionally retain one of the rivets therebetween with the longitudinal axis thereof vertically oriented, the, top plate member being cut away at one side of the opening to provide :a horizontal entrance for one rivet at a time into the topplate member, a mandrel supporting means below the plate members for holding the bottom of the mandrel with they upper end of the mandrel projecting freely through the opening in the bottom plate member,'a vibratory hopper, for feeding the rivets in a like-oriented manner with the 1ongitudinal axis thereof vertically disposed in succession to a point adjacent the top plate member, a horizontally extending pneumatically operated plunger for delivering one rivet at a time sideways through the entrance and into the opening in the top plate member, and a vertically disposed pneumatically operated press member aligned with the openings in the plate members and being movable fully into the opening in the top plate member for pushing two of the rivets retained in the top-and middle plate members into the middle and bottom plate members, respectively, and thereby freeing one of the rivets retained in the bottom plate member to slide down the,

placement of said tubular member and thereby open a control circuit of said pneumatically operated plunger and press member. 7

13. An apparatus as defined in claim 11, wherein said press member includes a ram having a rivet engaging lower end surface and a longitudinal bore extending to said lower end surface, and a spring biased rivet guiding pin in said bore and retractably projecting downwardly from said lower end surface, for reception in the, central bore of the rivets.

ReferencesCited by the Examiner UNITED STATES PATENTS 2,004,464 6/1935 Clarkson 29-241 X 2,403,443 7/1946 Knab 29-241 X 2,758,433 8/1956 Birchler et al. 29--241 X 3,014,601 12/1961 Swanson ,2148

WILLIAM FELDMAN, Primary Examiner.

J. C. PETERS, Assistant Examiner. 

1. AN APPARATUS FOR THREADING ARTICLES EACH HAVING A CENTRAL BORE THERETHROUGH ONTO A WIRE MANDREL, SAID APPARATUS COMPRISING AN ARTICLE RETAINING MEANS HAVING AN ARTICLE RECEIVING OPENING THERETHROUGH, A MANDREL SUPPORTING MEANS AT ONE SIDE OF SAID RETAINING MEANS FOR HOLDING THE MANDREL WITH ONE FREE END PROJECTING INTO SAID OPENING, SAID RETAINING MEANS HAVING RESILIENT MEANS ABOUT SAID OPENING FOR ENGAGING ONE OF THE ARTICLES AND FRICTIONALLY RETAINING SAID ONE ARTICLE IN SAID OPENING WITH THE FREE END OF THE MANDREL PROJECTING INTO THE BORE OF SAID ONE ARTICLE TO THEREBY CENTRALIZE SAID FREE END IN SAID OPENING, A HOLDING MEANS ADJACENT THE OPPOSITE SIDE OF THE RETAINING MEANS AS THE MANDREL SUPPORTING MEANS AND ADAPTED TO HOLD ANOTHER OF THE ARTICLES WITH THE BORE THEREOF ALIGNED WITH THE CENTRAL AXIS OF THE OPENING IN SAID RETAINING MEANS, MEANS FOR FEEDING ARTICLES ONE AT A TIME INTO SAID HOLDING MEANS, AND A PRESS MEANS FOR PUSHING THE ARTICLE HELD IN THE HOLDING MEANS TO THEREBY REPLACE SAID ONE ARTICLE IN SAID OPENING WHEREBY SAID ONE ARTICLE WILL BE RELEASED FROM SAID RETAINING MEANS TO SLIDE FREELY ALONG SAID MANDREL. 